Numerical Simulation of Aerodynamic Noise in a Turbocharger

Turbocharger is an important part of the turbocharged diesel engine. Due to the increase of mass flow rate and pressure ratio, aerodynamic noise of turbocharger has become more apparent. And turbocharger noise becomes one of the major noise sources of the main engine system of the ship. In the paper, the aerodynamic noise is predicted by using Computational fluid mechanics (CFD) and indirect boundary element method (IBEM) based on Lighthill acoustic analogy theory. Unsteady viscous flow in the centrifugal Compressor is simulated with finite volume method using the single stator and rotor blade passages and the characteristic of compressor is agreed well with the experimental value. The flow field characteristics and frequency spectrum of the fluctuating pressure are analyzed which agree well with the theoretical value. Dipole is the main noise source in compressor and the datum of pressure fluctuation at rotor blade are extracted. The boundary element model of the volute is established and the scattering effect on sound propagation is taken into account. Using indirect boundary element method, radiation noise field at compressor entrance at the blade passing frequency and its harmonics are predicted. The results can provide a useful reference to low noise design and structure optimization of centrifugal compressor.